Apparatus for additively manufacturing three-dimensional objects

ABSTRACT

Apparatus (1) for additively manufacturing of three-dimensional objects by means of successive layerwise selective irradiation and consolidation of layers of a build material which can be consolidated by means of an energy beam, with a stream generating unit (2) configured to generate a stream of a process gas (3) being capable of being charged with particles (4), in particular non-consolidated particulate build material and/or smoke and/or smoke residues, generated during operation of the apparatus (1) and a filter unit (5) configured to separate particles (4) from the stream of process gas (3), wherein the filter unit (5) comprises a filter chamber (6) with at least one filter element (7) at least partly arranged in the streaming path of the generated stream of process gas (3), wherein particles (4) in the stream of process gas (3) are separated from the process gas (3) by the filter element (7), wherein a particle reception chamber (13, 26, 28) is separably connected or connectable to a particle outlet (11) of the filter chamber (6) and configured to receive the particles (4) separated from the process gas (3).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to European Patent Application serialnumber 17 182 649.8 filed Jul. 21, 2017, and U.S. patent applicationSer. No. 16/022,538 filed Jun. 28, 2018, the contents of which areincorporated herein by reference in their entirety as if set forthverbatim.

The invention relates to an apparatus for additively manufacturingthree-dimensional objects by means of successive layerwise selectiveirradiation and consolidation of layers of a build material which can beconsolidated by means of an energy beam, with a stream generating unitconfigured to generate a stream of a process gas being capable of beingcharged with particles, in particular non-consolidated particulate buildmaterial and/or smoke and/or smoke residues, generated during operationof the apparatus and a filter unit configured to separate particles fromthe stream of process gas, wherein the filter unit comprises a filterchamber with at least one filter element at least partly arranged in thestreaming path of the generated stream of process gas, wherein particlesin the stream of process gas are separated from the process gas by thefilter element.

Respective apparatuses for additively manufacturing three-dimensionalobjects are widely known and may be embodied as selective lasersintering apparatuses, selective laser melting apparatuses or selectiveelectron beam melting apparatuses, for instance.

During operation of respective additive manufacturing apparatuses, anefficient removal of particles, such as non-consolidated particulatebuild material, particularly smoke or smoke residues, generated duringoperation of the apparatuses, without raising build material particlesfrom the powder bed, which is a decisive factor for the quality of theobject to be manufactured, can be challenging. In other words, thestream generating devices of respective apparatuses should be configuredto generate a gaseous fluid stream which, while streaming through theprocess chamber, on the one hand efficiently removes non-consolidatedbuild material particles from the process chamber and on the other handavoids raising build material particles from the powder bed. Thisparticularly, applies to additive manufacturing apparatus implementinghigh power energy beams, e.g. energy beams having a power of more than210 W.

Further, it is a task of filter units of respective additivemanufacturing apparatuses to separate particles contained or charged inthe process gas from the stream of process gas to ensure that only cleanprocess gas is recycled into the process chamber and can again becharged with particles generated during the operation of the apparatus.Thus, only process gas free from respective particles is streamed intothe process chamber, avoiding a contamination of the build process byparticles in the process gas. Particles separated from the process gastypically accumulate on the filter element and/or in the filter chamber.

Therefore, it is necessary that the filter element and/or the filterchamber is cleaned or replaced which leads to a downtime of theapparatus, wherein a manufacturing process has to be paused. Thus, atime-consuming cleaning or exchanging process of the filter elementand/or the filter chamber has to be performed.

In view of the above, it is the object of the invention to provide anapparatus for additively manufacturing of three-dimensional objectshaving an improved filter unit allowing for a reduction of downtimesand/or a reduction of the effort of cleaning and/or changing the filterelement and/or the filter chamber.

This object is achieved by an apparatus for additively manufacturingthree-dimensional objects according to claim 1. The claims depending onclaim 1 relate to possible embodiments of the apparatus according toclaim 1.

The apparatus described herein is an apparatus for additivelymanufacturing three-dimensional objects, e.g. technical components, bymeans of successive layerwise selective irradiation and consolidation oflayers of a powdered build material (“build material”) which can beconsolidated by means of an energy beam. A respective build material canbe a metal, ceramic or polymer powder. A respective energy beam can be alaser beam or an electronic beam. A respective apparatus can be aselective laser sintering apparatus, a selective laser melting apparatusor a selective electron beam melting apparatus, for instance.

The apparatus comprises a number of functional units which are usedduring its operation. Exemplary functional units are a process chamber,an irradiation device which is configured to selectively irradiate abuild material layer disposed in the process chamber with at least oneenergy beam, and a stream generating device which is configured togenerate a gaseous fluid stream at least partly streaming through theprocess chamber with given streaming properties, e.g. a given streamingprofile, streaming velocity, etc. The gaseous fluid stream is capable ofbeing charged with non-consolidated particulate build material,particularly smoke or smoke residues generated during operation of theapparatus, while streaming through the process chamber. The gaseousfluid stream is typically inert, i.e. typically a stream of an inertgas, e.g. argon, nitrogen, carbon dioxide, etc.

The invention is based on the idea that a particle reception chamber isprovided that is separably connected or connectable to a particle outletof the filter chamber and configured to receive the particles separatedfrom the process gas. Therefore, the present invention suggests a filterelement that separates the particles, in particular non-consolidatedparticulate build material and/or smoke and/or smoke residues, from theprocess gas, wherein the particles do not accumulate on the filterelement or in the filter chamber but are received in a particlereception chamber that is connectable or connected to the filterchamber.

The particles are conveyed via the stream of process gas into the filterunit, where they come in contact with the filter element and areseparated from the stream of process gas. After being separated from thestream of process gas the particles arrive in, particularly fall into,the particle reception chamber. The particles therefore, do notaccumulate at the filter element and/or in the filter chamber but in theparticle reception chamber. Thus, there is no need to clean and/orchange the filter element as the filter element does not get filled orsaturated with particles.

Further, the invention suggests separably connecting the particlereception chamber with the filter chamber so that the particle receptionchamber can be separated from the filter chamber at any time. Hence, thefilter chamber is merely the location in which the particles areseparated from the stream of process gas but is not used to receive theparticles. After the particles are separated from the process gas insidethe filter chamber they arrive in the particle reception chamber,whereby the particle reception chamber can be separated from the filterchamber. If the particle reception chamber is filled to a defineddegree, the connection between the particle reception chamber and thefilter chamber can be closed and the particle reception chamber can bemechanically disconnected from the filter chamber, for example to cleanand to empty the particle reception chamber. Self-evidently it is alsopossible, to change the particle reception chamber if it is filled to acertain degree therefore, providing an interchangeable system ofparticle reception chambers, wherein a particle reception chamber thatis full or filled to a certain degree can be replaced by an emptyparticle reception chamber. By way of the invention it is possible, toreduce or even avoid downtimes related to the need for cleaning and/orreplacing the filter element and/or the filter chamber. Further, theparticle reception chamber or the particle reception chambers can bebuilt as separate units which can be separately handled independent ofthe apparatus.

It is particularly possible that more than one particle receptionchambers may be provided, whereby the particle reception chambers can beused successively or simultaneously, wherein for example a connection ofthe filter chamber to a first particle reception chamber may be closedwhen a fill level of the first particle reception chamber reaches apredefined level and a connection of the filter chamber to a secondparticle reception chamber may be opened to receive the particlesseparated by the filter element. The first particle reception chambercan then be mechanically disconnected from the filter unit and becleaned and/or replaced. After cleaning and/or replacing the firstparticle reception chamber a fresh or the fresh first particle receptionchamber may again be mechanically connected to the filter unit and assoon as a fill level of particles inside the second particle receptionchamber reaches a predefined level the second particle reception chambermay be separated from the filter chamber and the first particlereception chamber may be connected to the filter chamber while thesecond particle reception chamber may be mechanically disconnected andcleaned and/or replaced.

According to a possible embodiment of the apparatus, the particlereception chamber is separable from the filter chamber via a separationmeans, in particular a valve, wherein a connection between the filterchamber and a particle reception chamber is closed, whereby the filterchamber and the particle reception chamber remain mechanically connectedand/or the particle reception chamber is separable in that the particlereception chamber is mechanically disconnected from the filter chamber.According to this embodiment the particle reception chamber may beseparated or connected to the filter chamber in terms of a connectionbetween the volumes of the filter chamber and the particle receptionchamber, wherein a separation means, for example a valve, may be used toseparate both chambers or volumes, respectively, from each other. Inthis separated state the particle reception chamber can still bemechanically connected with the filter unit but it is not possible forparticles to pass from the filter chamber into the particle receptionchamber.

Further it is possible that in addition to the separation of the filterchamber from the particle reception chamber, the particle receptionchamber may be mechanically disconnected from the filter chamber and maytherefore, be moved away from the filter unit, for example to a locationwhere the particle reception chamber may be cleaned or emptied.Self-evidently both different states of connection or separation arepossible while connecting the particle reception chamber to the filterchamber so that a particle reception chamber may be merely mechanicallyconnected but still separated in that it is not possible for particlesto pass from the filter chamber into the particle reception chamber aslong as the separation means is in a closed state. After the separationmeans is in an opened state and therefore, a connection between thefilter chamber and the particle reception chamber is established,particles may pass from the filter chamber into the particle receptionchamber.

According to another embodiment of the apparatus, the particle receptionchamber is located below the filter chamber. Therefore, the particlesseparated by the filter element inside the filter chamber may fall downdue to gravity and pass from the filter chamber into the particlereception chamber. Of course, it is also possible to arrange theparticle reception chamber in any other position relative to the filterchamber, wherein a conveying device is used to convey the particlesseparated by the filter element into the particle reception chamber. Byarranging the particle reception chamber below the filter chamber it ispossible to use gravity to convey the particles into the particlereception chamber without additional effort. Hence, a particle outletcan be arranged bottom sides inside the filter chamber, for examplebelow the filter element.

The apparatus can further be improved in that the filter unit comprisesat least one particle guide element, in particular build as a funnel orfunnel-shaped, configured to guide particles that are separated from thestream of process gas by the filter element from the filter chamber tothe particle reception chamber. The particle guide element preferably isshaped in that particles falling down from the filter element onto theguide element are guided towards the particle outlet and therefore, moveto the particle reception chamber. Preferably, the particle guideelement is built as a funnel or funnel-shaped so that particles fallingdown from the filter element anywhere inside the filter chamber fall onthe surface of the guide element that is sloped towards the particleoutlet of the filter chamber. Additionally, it is also possible to use aconveying means to support the conveyance of particles inside the filterchamber, in particular on the surface of the guide element. Such aconveying means may be an oscillating conveyor configured to oscillatethe particle guide element to support the movement of the particlestowards the particle outlet and therefore, into the particle receptionchamber.

Advantageously, the filter element comprises a cylindrical shape toprovide a possibly large surface therefore, ensuring an effectiveseparation of the particles from the process gas. Further, it ispossible, that the filter element comprises a tapered shape on the sidefacing the particle outlet of the filter chamber. The filter element isarranged inside the filter chamber between a process gas inlet and atleast one process gas outlet of the filter chamber in that the processgas streaming into the filter chamber has to pass the filter elementbefore it reaches the process gas outlet of the filter chamber. By wayof this embodiment it can be assured that all of the process gas passesthe filter element, wherein the particles are separated from the processgas so that only cleaned process gas is recycled into the processchamber of the apparatus.

According to another preferred embodiment of the apparatus, the particlereception chamber is inseparably connected to the particle outlet of thefilter units by at least one valve. Thus, the particle reception chambermay be selectively separated from the filter chamber corresponding tothe opening state of the at least one valve. By providing a valve it canbe assured that the inertization of the filter chamber and the particlereception chamber is upheld when disconnecting the particle receptionchamber from the filter chamber. Further, it can be controlled whetherparticles may pass from the filter chamber into the particle receptionchamber, especially when more than one particle reception chamber isconnected to the filter chamber.

It is particularly preferred that the at least one valve is a splitvalve, in particular a split butterfly valve, and/or at least two discvalves are provided, wherein a first disc valve is controlledpneumatically and a second disc valve is controlled manually. Therefore,either the at least one valve is a split valve, wherein both theparticle outlet of the filter chamber and the particle inlet of theparticle reception chamber are sealed by the split valve are there aretwo separate valves, wherein one of the valves seals the particle outletof the filter chamber and one valve seals the particle inlet of theparticle reception chamber. In using two separate valves the valvesealing the filter chamber is preferably controlled pneumatically andthe valve sealing the particle reception chamber is controlled manually.

The apparatus can further be improved in that the particle receptionchamber is movable, in particular drivable, in the connected state.Hence, the particle reception chamber may be moved, for example from theposition in which it is connected to the filter chamber to a position inwhich the particle reception chamber may be cleaned or emptied.Self-evidently, it is possible to move the particle reception chamber toany arbitrary location. In particular, the particle reception chambermay be driven, for example by an integrated drive unit, for example amotor. Hence, when the particle reception chamber is in a disconnectedstate, i.e. the particle reception chamber is separated and mechanicallydisconnected from the filter chamber it is assigned to, the particlereception chamber can be moved away from the filter unit. This allowsfor an efficient cleaning or emptying process, in which for example anempty reception chamber may be moved to the filter chamber and aparticle reception chamber that is filled to a certain degree is movedaway for cleaning and/or emptying.

According to a preferred embodiment of the apparatus, at least oneprocess gas outlet of the filter unit is arranged upstream of a processgas inlet of the stream generating unit. The stream generating unittherefore generates a suction stream of process gas with respect to thefilter unit, wherein process gas is sucked through the filter unit andaccordingly through the filter element arranged inside the filterchamber of the filter unit. The process gas that passed the filterelement streams into the process gas outlet of the filter unit which isconnected to a process gas inlet of the stream generating unit locateddownstream of the filter unit. Therefore, a closed process gas cycle canbe obtained.

The apparatus can further be improved in that a passivation unit isprovided that is connected or connectable with the particle receptionchamber, wherein the passivation unit is configured to fill passivatingmaterial, preferably water or passivation material in powder form, intothe particle reception chamber. Therefore, an oxidation of the particlesseparated from the process gas can be avoided since the particles insidethe particle reception chamber are passivated via the passivatingmaterial. The passivating material may be filled into the particlereception chamber, for example sprayed or sprinkled in that theparticles are wetted or moistened. Thereby, a safe opening of theparticle reception chamber may be assured as the particles received inthe particle reception chamber are passivated to reduce the risk of anexplosion or a deflagration of the particles coming in contact with forexample oxygen of the ambient air.

The previously described embodiment can further be improved in that theparticle reception chamber comprises a fill level indicator configuredto indicate a fill level of particles and/or passivating material insidethe particle reception chamber. Thus, a fill level can be communicatedto a user and/or a control unit to indicate if or when cleaning orreplacing of the particle reception chamber is necessary. According to asignal of the fill level indicator a cleaning process and/or a changeprocess of the particle reception chamber may be initiated by the userand/or by a control unit assigned to the apparatus.

Besides, the invention relates to a filter unit for an apparatus foradditively manufacturing of three-dimensional objects by means ofsuccessive layerwise selective irradiation and consolidation of layersof a build material which can be consolidated by means of an energybeam, in particular an apparatus as described before, wherein the filterunit comprises a particle reception chamber that is separably connectedor connectable to a particle outlet of the filter chamber and isconfigured to receive the particles separated from the process gas.Self-evidently, all features details and advantages described withrespect to the apparatus are fully transferable to the filter unit.

The invention further relates to a plant for additively manufacturing ofthree-dimensional objects, comprising a plurality of apparatuses foradditively manufacturing of three-dimensional objects by means ofsuccessive layerwise selective irradiation and consolidation of layersof a build material which can be consolidated by means of an energybeam, in particular apparatuses as described above, wherein the particleoutlets of at least two filter units are connected to at least onecommon particle guide means connected to at least one common particlereception chamber. Self-evidently, all features details and advantagesdescribed with respect to the apparatus and/or the filter unit are fullytransferable to the plant and vice versa.

Therefore, the plant comprises a plurality of apparatuses for additivelymanufacturing of three-dimensional objects, wherein each of theapparatuses comprises at least one filter unit with at least one filterchamber. The particle outlets of the filter chambers of the filter unitsare connected to at least one common particle guide means. Thus,according to this embodiment it is not necessary to provide a separateparticle reception chamber for each of the filter units or filterchambers, respectively, but to provide a common particle guide means inwhich the particles separated by the filter elements inside therespective filter chambers arrive. The common particle guide means isconnected to a common particle reception chamber in which the particlesfiltered by the various filter units are received. Of course, it ispossible to provide a plurality of common particle reception chambersand also a plurality of common particle guide means. Hence, theconnection of the filter chambers of the filter units with the commonparticle guide means does not have to be separable or disconnectable,but it is preferred to have a separation means in the region of theparticle outlet of each filter chamber to control the amount ofparticles that enter the common particle guide means via each filterchamber.

Preferably the common particle reception chamber again is separable anddisconnectable from the common particle guide means to ensure anefficient cleaning or emptying process of the common particle receptionchamber. Thus, it is possible to separate and disconnect the commonparticle reception chamber to clean the common particle receptionchamber and/or change the particle reception chamber, for example if adefined filling level of particles in the particle reception chamber isreached or exceeded. Therefore, the common particle reception chamberdoes not have to be cleaned or emptied in place, but it is possible toreplace a filled common particle reception chamber with another commonparticle reception chamber, i.e. an empty common particle receptionchamber.

The plant further preferably comprises a passivation unit configured togenerate a stream of passivating material or a stream of fluidcontaining passivating material between an inlet of the common particleguide means to the common particle reception chamber. Therefore, thestep of passivating the particles and the step of conveying theparticles to the common particle reception chamber can be integratedinto one process step as the passivation unit according to thisembodiment is configured to create a stream of fluid containingpassivating material or a stream of passivating material that can becharged with the particles entering the common particle guide means fromthe various particle outlets of the filter chambers of the filter units.Therefore, the particles entering the common particle guide means arereceived by the stream generated by the passivating unit that conveysthe particles in streaming direction, wherein the particles aresimultaneously passivated by coming in contact with the passivatingmaterial.

Advantageously, the particles that are separated in the filter units ofthe various apparatuses assigned to the plant are conveyed via thegenerated stream of passivating material.

Exemplary embodiments of the invention are described with reference tothe FIG. The FIG. are schematic drawings, whereby

FIG. 1 shows a principle drawing of an apparatus for additivelymanufacturing three-dimensional objects according to an exemplaryembodiment;

FIG. 2 shows a detail of an apparatus for additively manufacturingthree-dimensional objects according to an exemplary embodiment;

FIG. 3 shows a filter unit of an apparatus for additively manufacturingthree-dimensional objects according to an exemplary embodiment;

FIG. 4 shows a filter unit of an apparatus for additively manufacturingthree-dimensional objects according to an exemplary embodiment; and

FIG. 5 shows a plant comprising two apparatuses for additivelymanufacturing three-dimensional objects according to an exemplaryembodiment.

FIG. 1 shows an apparatus 1 for additively manufacturing ofthree-dimensional objects by means of successive layerwise selectiveirradiation and consolidation of layers of a build material which can beconsolidated by means of an energy beam. The apparatus 1 comprises astream generating unit 2 configured to generate a stream of a processgas 3 (indicated by arrows) being capable of being charged withparticles 4, in particular non-consolidated particulate build materialand/or smoke and/or smoke residues, generated during operation of theapparatus 1 and a filter unit 5 configured to separate particles 4 fromthe stream of process gas 3. The filter unit 5 comprises a filterchamber 6 with at least one filter element 7 at least partly arranged inthe streaming path of the generated stream of process gas 3, whereinparticles 4 in the stream of process gas 3 are separated from theprocess gas 3 by the filter element 7.

The process gas 3 enters the filter chamber 6 via a process gas inlet 8and exits the filter chamber 6 via a process gas outlet 9. As can beseen from FIG. 1 the filter element 7 is arranged inside the fill thechamber 6 between the process gas in that 8 and the process gas outlet9. The filter element 7 has a cylindrical shape, wherein particles 4that are conveyed via the stream of process gas 3 into the filterchamber 6 come in contact with the filter element 7 and are therebyseparated from the stream of process gas 3. The separated particles 4fall down due to gravity and come in contact with a surface of aparticle guide element 10 that is essentially funnel-shaped. Theparticle guide element 10 guides the particles 4 to a particle outlet 11of the filter chamber 6. The particle outlet 11 of the filter chamber 6is separately connected to a particle inlet 12 of a particle receptionchamber 13 of the filter unit 5.

FIG. 1 further shows that in the region of the particle outlet 11 and inthe region of the particle inlet 12 a valve 14 is provided. Therefore,the connection between the filter chamber 6 and the particle receptionchamber 13 of the filter unit 5 can be disconnected via the valves 14.In other words the opening or closing state of the valves 14 controlswhether particles 4 can pass from the filter chamber 6 into the particlereception chamber 13 via the particle outlet 11 and the particle inlet12.

As can further be derived from FIG. 1 the particle reception chamber 13can be disconnected from the filter chamber 6 of the filter unit 5(depicted via a dashed line 15). Hence, it is possible, to close thevalves 14 and therefore separate the particle reception chamber 13 fromthe filter chamber 6. Afterwards, the particle reception chamber 13 canbe mechanically disconnected from the rest of the filter unit 5 and canbe moved away, for example to a station in which the particle receptionchamber 13 is cleaned and/or emptied.

The stream generating unit 2 that generates the stream of process gas 3is located downstream of the filter unit 5. In other words a process gasinlet 16 of the stream generating unit 2 is connected to a process gasoutlet 9 of the filter unit 5. Therefore, the stream generating unit 2only takes in process gas 3 that is rinsed of particles 4 via the filterunit 5. The stream of process gas 3 that enters a process chamber 17 ofthe apparatus 1 therefore, is free of particles 4.

Additionally the apparatus 1 depicted in FIG. 1 comprises a pressuregenerating means 18 located topsides of the filter unit 5 and comprisesa nozzle that extends into the inside or near the filter element 7. Viathe pressure generating means 18 it is possible to generate anoverpressure inside the filter chamber 6 to solve particles 4 thataccumulated on the surface of the filter element 7.

FIG. 2 shows an alternative exemplary embodiment of the valve 14 inwhich the valve 14 is built as a split butterfly valve. Hence, thesealing of the particle reception chamber 13 and the filter chamber 6and the mechanical disconnection of the particle reception chamber 13from the rest of the filter unit 5 is integrated into the valve 14 beingbuilt as a split butterfly valve.

FIG. 3 shows an apparatus 1 as described before, wherein the particlereception chamber 13 comprises moving means 19. Therefore, the particlereception chamber 13 is movable via the moving means 19, in particulardrivable via a motor connected to the moving means 19. It is furtherpossible to arrange a motor or a driving unit in general, outside orseparate to the particle reception chamber 13.

FIG. 4 shows an apparatus 1 according to another exemplary embodiment.The apparatus 1 is basically built like the apparatus 1 as describedbefore, therefore, the same numerals are used for the same components ofthe apparatus 1. Deviant from or additional to the apparatuses 1described before the apparatus 1 depicted in FIG. 4 comprises apassivation unit 20 separably connected with the particle receptionchamber 13. The passivation unit 20 is configured to fill passivatingmaterial 21 (depicted by an arrow) into the particle reception chamber13. The passivating material 21 is preferably water, wherein any otherpassivating material 21 may be used that is configured to passivate theparticles 4 inside the particle reception chamber 13, for examplepassivating material in powder form. To passivate the particles 4 insidethe particle reception chamber 13 a valve 14 is provided in theconnection between the passivation unit 20 and the particle receptionchamber 13. Dependent on an opening state of the valve 14 thepassivating material 21 can be filled into the particle receptionchamber 13, for example sprayed, wherein the particles 4 can be wettedor moistened.

FIG. 4 further shows a fill level indicator 22 that is configured toindicate a fill level of particles 4 and/or passivating material 21inside the particle reception chamber 13. The fill level indicated bythe fill level indicator 22 can further be sent to a control unit 23 sothat corresponding process steps can be initiated by the control unit23, such as the initiation of a change and/or a separation of theparticle reception chamber 13 from the rest of the filter unit 5.Self-evidently, the control unit 23 may also control the opening stateof the valves 14 and any other component of the apparatus 1 necessaryfor the manufacturing cycle.

FIG. 5 shows a plant 24 exemplary comprising two apparatuses 1. Ofcourse, the plant 24 can comprise a plurality of apparatuses 1 but forthe sake of simplicity only two apparatuses 1 are depicted in this FIG.There are two filter units 5 assigned to the plant 24, wherein theparticle outlets 11 of the filter chambers 6 of the filter units 5 areseparably connected to a common particle guide means 25. The commonparticle guide means 25 is configured to convey the particles 4 that arefilled in from the filter chambers 6 of the filter units 5 via theirparticle outlets 11 and are conveyed inside the common particle guidemeans 25 to a common particle reception chamber 26. Therefore, apassivation unit 20 is assigned to the plant 24 generating a stream ofpassivating material 21 and/or a stream of fluid containing passivatingmaterial 21. The passivating material 21 is filled into the commonparticle guide means 25 and conveys the particles 4 inserted into thecommon particle guide means 25 via the particle outlets 11 of the filterunits 5 to the common particle reception chamber 26. Thereby, theparticles 4 entering the common particle guide means 25 are not onlyconveyed to the common particle reception chamber 26 but are passivatedat the same time as they come in contact with the passivating material21 as soon as they enter the common particle guide means 25.

FIG. 5 shows that a second common particle guide means 27 is providedthat conveys the particles 4 and the passivating material 21 to a secondcommon particle reception chamber 28. Of course, an arbitrary amount ofcommon particle guide means 25, 27 and common particle receptionchambers 26, 28 can be provided. It is also possible, to arrange andconnect the various common particle guide means 25, 27 and the variouscommon particle reception chambers 26, 28 in an arbitrary manner.

All features, advantages and details depicted in the FIGS. 1 to 5 arearbitrarily interchangeable and transferable to all the embodiments.

The invention claimed is:
 1. A method of filtering charged particlesfrom a stream of process gas circulating through a system foradditively-manufacturing three-dimensional objects, the methodcomprising: circulating the stream of process gas through one or morestreaming paths, the stream of process gas generated by one or morestream generating units, and the one or more streaming pathsrespectively comprising a process chamber inlet and a process chamberoutlet; flowing the stream of process gas through a process chamber ofrespective ones of a plurality of apparatuses configured to additivelymanufacture three-dimensional objects by successive layerwise selectiveirradiation and consolidation of layers of a powdered build material;accumulating charged particles in the stream of process gas flowingthrough the process chamber; removing charged particles with the streamof process gas flowing through the process chamber; flowing the streamof process gas having accumulated charged particles through one or morefilter units disposed along respective ones of the one or more streamingpaths, the one or more filter units thereby separating the chargedparticles from the stream of process gas; receiving charged particleshaving been separated from the stream of process gas in one or moreparticle reception chambers respectively coupled to the one or morefilter units by one or more particle guides; supplying a passivatingmaterial from a passivation unit to the one or more particle guidesand/or the one or more particle reception chambers; sealing the one ormore particle reception chambers via a valve; and moving, with a drivingunit, the one or more particle reception chambers.
 2. The method ofclaim 1, comprising: moving the charged particles having been separatedfrom the stream of process gas to the one or more particle receptionchambers at least in part using a stream of the passivating material ora stream of fluid containing the passivating material.
 3. The method ofclaim 1, comprising: closing a particle outlet of a respective one ofthe one or more filter units; and decoupling the respective one of theone or more particle reception chambers from the one or more particleguides.
 4. The method of claim 3, wherein the particle outlet comprisesa valve configured to close the particle outlet and the particle inlet.5. The method of claim 3, wherein the one or more particle guidesrespectively comprise one or more valves configured to close theparticle outlet and the particle inlet.
 6. The method of claim 1,wherein the driving unit comprises a movement assembly comprising aplurality of wheels for moving a respective one of the one or moreparticle reception chambers when decoupled from the one or more particleguides.
 7. The method of claim 6, comprising: detecting with a filllevel indicator, an indication of a fill level of particles and/orpassivating material inside the respective one of the one or moreparticle reception chambers; and closing a particle outlet of arespective one of the one or more filter units and sealing therespective one of the one or more particle reception chambers based atleast in part on the indication of the fill level detected with the filllevel indicator.
 8. The method of claim 1, wherein the charged particlescomprise non-consolidated particulate build material, smoke, and/orsmoke residues.
 9. The method of claim 1, wherein the passivatingmaterial comprises water or a powder.
 10. The method of claim 1, whereinthe one or more filter units each comprise a filter element.
 11. Themethod of claim 10, wherein an overpressure displaces charged particlesthat accumulate on a surface of the filter element.
 12. The method ofclaim 1, wherein the passivating material from the passivation unit issupplied to the one or more particle reception chambers.
 13. The methodof claim 1, wherein the valve is a split butterfly valve.
 14. The methodof claim 1, wherein the one or more particle reception chambers aredrivable via the driving unit.
 15. The method of claim 1, wherein thepassivating material moistens the charged particles.
 16. The method ofclaim 1, wherein the passivating material passivates the chargedparticles inside the one or more particle reception chambers.
 17. Themethod of claim 1, wherein the passivating material is supplied to theone or more particle reception chambers via spraying.
 18. The method ofclaim 1, wherein a valve is provided in a connection between thepassivation unit and the one or more particle reception chambers. 19.The method of claim 1, wherein following separation of the chargedparticles from the stream of process gas, the stream of process gas issupplied from the one or more filter units to the one or more streamgenerating units.
 20. The method of claim 1, wherein the passivatingmaterial from the passivation unit is supplied to the one or moreparticle guides.